Head box for paper making machines



Jan. 27, 1959 W. S. CORBIN ET AL HEAD BOX FOR PAPER MAKING MACHINESFiled NOV. 6, 1952 3 Sheets-Sheet 1 IN VEN TOR.S

M/cs/ey 5 Cor/in Henr/K W1 Iden r/es lq arson A orney.

Jan. 27, 1959 w. s. CORBIN ET AL 2,870,690

HEAD BOX FOR PAPER MAKING MACHINES 3 Sheets-Sheet 2 Filed Nov. 6, 1952 Mm m M DIZIK /es W Walks; BY A223 ol r; ep

Jan. 27, 1959 w. s. CORBIN ET AL 2,370,690

HEAD BOX FOR PAPER MAKING MACHINES 3 Sheets-Sheet 3 Filed Nov. 6, 1952J1 Is-. E

INVENTORS 5. Corbin United States Patent F HEAD BOX FOR. PAPER MAKINGMACHINES Wesley S. Corbin, Charles M. Pearson, and Henrik Walden,Watertown, N. Y., assignors, by mesne assignments, to The Black-ClawsonCompany, Hamilton, Ohio, a corporation of Ohio Application November 6,1952, Serial No. 319,157

11 Claims. (Cl. 92-44) This invention relates to head boxes forFourdrinier paper making machines.

The invention has as an object a head box embodying a construction suchthat the box will perform efiiciently over a wide range of weights ofpaper and speeds of paper on the machine. For example, this head boxwill operate efficiently over a range of speeds of 125 feet to 1000 feetper minute and on a basic weight range of from 25 lbs. to 125 lbs., andwith a stock consistency. range varying from .3% to .7% fiber.

This performance is obtained by keeping the flow of stock through thesuccessive passages of the box under what might be termed controlledagitation up to the time the stock is discharged through the slice lip,the invention embodying a structural arrangement by which the box can beadjusted for such controlled agitation of the stock for differentconsistencies of stock moving at different velocities.

The invention :has as a further object the provision of means for theremoval of air from the stock so when the stock is discharged throughthe slice, it is practically free from entrapped air.

The invention has as a further object a head box embodying a structuralarrangement which minimizes the collection of slime and fiocs of fiber.I

The invention consists in the novel features and in the combinations andconstructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanyingdrawings in which like characters designate corresponding parts in allthe views.

In the drawings Figure 1 is a side elevational view of a head boxembodying our invention.

Figure 2 is a front elevational view of the head box with parts brokenaway and parts in section.

Figure 3 is a vertical sectional view taken on line 3-3, Figure 2.

Figure 4 is an enlarged fragmentary sectional view taken on line 4-4,Figure 3.

The head box comprises a heavy casting or structural base member mountedupon asuitable concrete foundation 10. This base member is formed withan upper concave wall 11 which merges with a downwardly extendingportion 12 to form a permanent ridge 12' extending across the full widthof the head box. The forward end of the curved surface 11 joins ahorizontal forwardly extending portion 13 which is supported by avertically extending forward wall portion 14 and forms a portion of thelower slice lip.

The box proper is formed with side plates 15 resting at their loweredges on the concrete foundation 10 and being attached to the ends ofthe base member. The lower portions of the side plates 15 are formedwith forwardly extending portions 16. The bottom wall 17 of the box ispositioned upon the concave surface 11 of the base member following thecontour thereof and extending downwardly, as at 18, over the surface ofthe rear wall 2,870,690 Patented Jan. 27,1959

12 of the base, and being fixedly secured, as by welding, to one edge ofan inlet slot 20 formed in a tubular member 21' extending transverselyof the head box and suitably supported, as by a concrete foundation 22.

The rear wall 24 of the box is attached to its lower edge to theopposite edge of the slot 20.. The lower portion 25 of the rear wall andthe lower portion 27 of the depending bottom wall diverge outwardly andupwardly from the slot 20 and form the lower portion of an up-flowcompartment, the upper portion of which is formed by a partition memberdesignated generally 28 and consisting of plates 29, 30, 31, 32, 33, 34,extending transversely of the box. The lowermost plate 29 is positionedslightly above the ridge 12' or crest of the bottom wall'of'the box toprovide a slot 36 through which a portion of the stock flow passesforwardly into the lower endof the down-flow compartment which is formedby the partition 28 and the front wall 37 of the box. The uppermostplate 34 has its upper edge formed as shown in Fig. 3 with a convexlycurved face 38 on its forward side to provide for smooth flow of stockthereover with minimum tendency to cavitation and undesirable fiber orslime deposits such as may result from a flowv of stockover a verticalsurface. g p

The tubular inlet member 21 forms a stock inlet chamber 39 which isconnected to the stock supply through a plurality of rearwardlyextending flanged pipe members 40. The chamber 39 forms in effectanexplosion chamber, since the stock flowing through the inlet pipes 40vtravels at relatively high velocity and, due to the large crosssectional area of the member 21, the stock is permitted to expandsuddenly, so to speak, whereby the velocity is reduced and a high statichead is formed, creatin the first turbulence, or agitation, of thestock. f. The up-flow of stock through the inlet slot 20 is restrictedby a baffle 42 extending transversely of the box between the inclinedside walls 25, 27, and this bafile is of inverted teardrop shapeincluding side portions 44 converging upwardly to an apex 45. Thisbaffie is adjustable vertically toward and from the inlet slot 20.Because of the restriction by baffle 42 of the flow area between itselfand the sides 25, 27, the velocity of the stock is again increased, butas it flows upwardly into the broader portion of the up-flowcompartment, the velocity is decreased. The inverted teardroparrangement of battle 42 promotes smooth deceleration of this upwardflow of stock with minimum tendency to cavitation.

To the inner surface of each end wall 15 of the box, there are fixedlysecured, as by welding, a plurality of pairs of angle strips 48, seeFigure 4, these strips extend-v ing vertically in parallel spacedrelation and providing a T-slot in which there may be mounted spacingblocks 50. 1

This T-slot arrangement is to provide a mounting for baffles 51 in theup-flow and down-flow compartments.

In cross sectional form, the baffles51 are of tear-drop bafiles, and toeach end plate there is secured,"as by screws 57, a block 58 slidablymounted between the guide rails 48 for cooperation with spacing blocks50 of the proper selected heights to support the baflies 51 in thedesired positions.

respective The baffle 42 controlling the inlet slot 20 is constructedwith a shaft 60 extending therethrough and outwardly through verticallyarranged slots 61 in the end plates of rack 72 having a threaded stem 73extending through I a bracket 75 carried by the plate. 67, the stembeing prov ded with adjusting nuts- 76 above and below the bracket andby adjusting the nuts 76, the rack is moved vertically.

The bafile 42 is fixedly secured at each end to a sleeve encircling theshaft, the sleeves being also fixedly secured to the bearing members 64as by set screws, see Figure 2. With this arrangement the baffle isadjusted vertically at one side of the machine toward and from the inletslot and is restrained against rotation during such adjustment.

It is well known that every furnish or stock solution has itsflocculating time. This means that if the fibers in the stock remain inthe same relative condition, either because of stagnation, or uniformvelocity, for a certain period of time, the fibers will tend to becomeattached to eaehother and form clots or fiocs. There is a standard.procedure used in determining the time required to cause this so-called'flocculation of the fibers, and this flocculation time is standard forany given furnish. If at any time within theflocculating period, the fibers are violently agitated, or disturbed, 'the tendency to flocculationisbroken up. This flocculation of fibers is aserious probleminmanufacturing paper on a Fourdrinier machine. If the fibers aredischarged through the slice onto the forming wire in flocs or clots,the qualit-y of the sheet will be impaired, the non-uniform distributionof the fibers adversely affecting the quality of the-paper from autility standpoint.

The baflles 42, 51 are eflfective to reduceflocculation ofthe stock to aminimum and if the baflies are properly spaced apart, flocculation canbe entirely eliminated. As the flow of stock encounters each baflle, itsprogress is restricted in moving through the reduced area between thebaflle and the sides of the up-fiow and down-flow compartments. Thisrestriction causes an increase in the velocity of the movement of thestock, but after the stock has passed the baffle, its velocity isreduced. This periodic change in the velocity of the stock createsconsiderable agitation of the stock and, as previously pointed out, thisavoids flocculation of the fibers. The baflies 51 are spaced apartproper distances in accordance with the determined flocculation time ofthe stock. This-adjustment is by the employment of the spacer blocks 50positioned in the guide pieces 48. The bafiles, because of theirstructural arrangement, also serve an additional purpose.

Another problem in the manufacture of paper is caused by air entrappedand absorbed in the stock. The baffles of teardrop shape tend to collectsmall bubbles of air from the stock and to discharge them off the pointsor apexes 54. These bubbles rise rapidly in the up-flow compartment andcollect on the surface of the pond where they are eliminated.

Such air as remains in the stock during its downward flow, in thedown-flow compartment, tends to collect on and to follow down the.forward wall 37 of the box, and thebubbles passing off of the apexes 54of the baffles 51 likewise move toward the; wall 37.

The bottom wall of the box inclines downwardly, as

at 80, from the ridge 12' and the front wall of the up.- flowcompartment, and. forms the. bottom wall of a discharge compartment orpassage 81 which curvesupwardly and communicates with the slice opening82. The top wall 83 of the discharge compartment 81 likewise curvesupwardly and at the joinder of this wall with the front wall 37, thereis provided a slot 84 communicating with a compartment 85 provided atone or both ends with a suction outlet pipe 86. The slot 84- is in thenature of an air vent for removing the accumulation of air bubblestraveling down the surface of the front wall 37, and it will also beseen in Fig. 3 that since the slot 34 is located at a position wellbelow the ridge 12' where the wall 83 is formed to introduce aconsiderable restriction of the flow area of the compartment or passagev81, the resulting change of the pressure head to velocity promotes therelease of entrained'air bubbles at the top of this passage for removalby way of the slot 84.

There is journalled in the box and extending transversely in thedischarge compartment 81, a distributor roll 88, the top and bottomwalls of this passage diverging upwardly from the vicinity of the slot84 to enlarge the passage sufiiciently for reception of the distributorroll 88. This roll is mounted upon a shaft 8% journalled in bearingsmounted on the portions 16 of the side plates 15 of the box. One end ofthe shaft, as 91, extends outwardly through the bearing for thereception ofa pulley or gear to effect rotation of the roll. The rollconsists of a series. of disks 93 arranged in spaced apart relation onthe shaft with a plurality of rods 94 extending parallel with the shaft89 through the disks 93 adjacent the periphery thereof, as shown indetail in the copending application of W. S. Corbin, Serial No. 238,723,filed July 26, 1951, and assigned to the same assignee as thisapplication. The function of this roll is to eflect agitation of thestock without imparting movement thereof transversely of the box.

The top wall 83 of the discharge compartment 31 extends upwardly about aportion of the distributor roll 88, the roll being of such diameter thatits periphery moves in close adjacency to the bottom and top Walls ofthe compartment, whereby the roll is continually and completelysubmerged in the stock flowing through the discharge compartment. 81.

The forward lower portions 16 of the end walls 15 are provided at theirupper edges with laterally extending plates reinforced by brackets. 101.There is slidably mounted on the plates 100, a deck having end walls102, a bottom wall 103, and a top wall 104. The end walls 102 engage theinner surface of the wall portion 16 of the box and carry laterallyextending members 106 min forced with angle pieces 107, the members 106being slidably mounted upon the plates 100.

The deck structure is formed with a plurality of vertically extendingwalls or partitions 108, and a rear wall 109 to which bearing blocks 110are mounted and in which there is journalled a shaft 111 provided at oneend with a hand wheel 112. The shaft 111 carries a pair of wormv gears113 arranged in mesh with worm wheels 114 forming nuts for screws 115having eye heads attached to the forward Wall of the box, as by a rod116. With this. arrangement, rotation of the hand wheel 112 effectsforward and rearward movement of the deck structure. The bottomwall 103extends forwardly and upwardly from the roll 88 to the slice 82 forminga continuation ofthetop wall of the discharge compartment. An upperslice lip is hingedly secured to the front end of the bottom wall 103,and mechanism is provided for adjusting thisupper lip 12 0 toward andfrom the bottom lip of the slice 82. There is mounted on the top wall.104 of. the deck structure, a plurality of gear housings 12-2 in whichthere is journalled a shaft 123 extending horizontally and alsosupported in bearings 124 and. provided. on at least one end with a handwheel 125.; The shaft has fixed on it worms engaging with worm wheels128. which constitute nuts for screws 129 extending. vertically andbeing secured at their lower ends in housings 130. mounted for verticalsliding movement on a front wall 131 of the deck structures A beam inthe form of a tubular member 132 is carried by the housings; 130 andextends transversely across the front of the deck. A series ofrelatively closely placed screws 135 are attached to the forward edge ofthe lip 120 and extending through the beam 132, these screws beingprovided with upper and lower nuts, 136 to effect individual verticaladjustment of the screws to level the lipv 120, initial verticaladjustment of the lip being effected by rotation of the hand wheel 125.

As clearly shown in Fig.3, the ridge 12 is located in substantially thesame horizontal plane with the forming wire 140 where the latter leavesthe-breast roll 141.; The entire approach flow of stock to-the' wirethrough the discharge passage 81 is therefore below the .wire levelexcept for the short distance after leaving the distributor roll 88 tothe slice. It is accordingly apparent thatfsince some head of stock isrequired above the ridge-12', which even for minimum speeds will extendabove the ridge to a level appreciably higher than the upper; slice lip120, this construction assures both that the, distributor roll 88 beatall times completely submergedin stock, andalso that no part of thisdischarge passage will be above the liquid level during operation, thuspreventing possible drying and tendency to collect fiber thereon.

In addition, with the top Wall portion 103 of the discharge passageinclined upwardly from the distributor roll 88 to its junction with theupper slice lip 120 as shown, if air bubbles should travel with thestock beyond the slot 84, they will tend to migrate upwardly andoutwardly along the wall 103 until they are entrained by the scouringaction of the stock as discharged there by the slice. This dischargepassage construction therefore provides for control of the flowdistribution ofythe stock at a position close to the slice even atminimum speeds of operation, and at the same time it gives maximumassurance against possible depositing of air, slime or the like tendingto build up obstructions to smooth sheet formation as Well as to theformation of lumps capable of subsequently breaking off into thefiow'and forming defects in the sheet.

What we claim is: i t

' l. A head box for a Fourdrinier paper machinehaving a forming wire anda breast roll supporting the wire in a predetermined horizontal plane,comprising front and rear-walls and a pair of side walls defining a mainchamber for receiving the paper making stock', said chamber being opento atmospheric pressure at the top thereof, means including a bottomwall forming a ridge extending permanently across said main chamber anddefining therewith a rear and a front compartment, means for deliveringstock into said rear compartment for flow therefrom over said ridge tosaid front compartment, means forming a slice in substantially the samehorizontal' plane as the wire for delivering the stock from said frontcompartment to the wire, means including a top wall forming a dischargepassage leading from said front compartmentto said slice, meansestablishing said ridge at substantially the same horizontal level asthe wire to provide for slow speed operation of said head box with acorrespondingly low pressure head of stock abovesaid ridge, removablepartition means above said ridge 'for raising the height of said frontcompartment to increase the pressure head ofstock therein forcorrespondingly increasing speeds of operation, a distributor rolljournaled within said discharge passage for agitating the stock flowthrough said passage to even the flow distribution of the stock'therethrough, said top wall having a substantial portion of the lengththereof located below the horizontal level of said ridge and theremainder thereof located not substantially higher than said ridge tomaintain said distributor roll submerged in'stock through the full speedrange of operation of said head box, means forming a bleed chamber insaid head box located forwardly of said ridge, said top and said bottomwalls including portions located between said ridge and said distributorrollin relatively close proximity to each other to introduce arestriction in said discharge passage inter mediate said ridge and saiddistributor rolls with resulting change of the pressure head on thestock flowing therethrough to velocity promoting release .of entrainedair bubbles at the top of said restriction, means defining a slot insaid top wall extending substantially the fulldefining therewith a rearand a front compartment, means including partition members removablymounted above said ridge for extending the heights of said compartmentsin accordance with the desired pressure head of stock in said chamber,means for delivering stock into the lower; end of said rear compartmentfor flow upwardly therein andover said partition means to said frontcompartment, means forming a slice in substantially the same hori-.zontal plane as the wire for delivering the stock from said frontcompartment to the wire, at least one imperf'oratebafile memberextending between said side' walls in each of said compartments, saidbaffle members. beingof' generally teardrop configuration in crosssection providing a rounded surface on one side thereof tapering to anapex on the opposite side thereof, and means mounting said bafflemembers with the apex of each thereof pointing-in the direction'of stockflow therepast to cause sudden acceleration of said stock flow'followedby more gradual deceleration and thus to effect agitation of said stockwith minimum turbulence andtendency to. flocculation of the fiberstherein. a I I 3. A head box for a Fourdrinier paper machine having. aformingwire and a breast roll supporting the'wire'in a predeterminedhorizontal plane, comprising front and rear. walls and a pair of sidewalls defining. a main chamber for receiving the paper making .stock,said chamber being open to atmospheric pressure at'the top. thereof,means including a bottom wall forming a ridge, extending permanentlyacross said main chamber and defining therewith a rear and a frontcompartment, means including partition members removably mounted abovesaid ridge for extending the heights of said compartments in accordancewith the desired pressure head of stock in said chamber, means fordelivering stock into thelower end of said rear compartment for flowupwardly therein and over said partition means to said front compartment, means forming a slice in'gsubstantially the same horizontalplane as the wire for delivering the stock from said front compartmentto the wire, at least one imperforate baffle member extending betweensaid side walls in each of said compartments, said .baffle members beingof generally teardrop configuration in cross section providing a.rounded surface on one side thereof tapering to an apex on the oppositeside thereof,

means mounting said baffle members with the apex of each thereofpointing in the direction of stock flow-therepast to cause suddenacceleration of said stock flow followed by more gradual decelerationand thus to effect agitation of said stock with minimum turbulence-andtendency to flocculation of the fibers therein, and the uppermost ofsaid partition members having a convex surface on the side thereoffacing said front compartment to minimize cavitation in the flow ofstock over asro geao *2 wire in a predetermined horizontal plane,comprising frontand rear walls and a pair of side walls defining a mainchamber for receiving the paper making stock, said chamber being open toatmospheric pressure at the top thereof, means including a bottom wallforming a ridge extending permanently across said main chamber anddefining therewith a rear and a front compartment, meansincludingpartition members removably mounted above said ridge for extending theheights of said coinpartments in accordance with the desired pressurehead of stock in said chamber, means for delivering stock into the lowerend of said rear compartment for flow upwardly: therein and over saidpartition means to said front compartment, means forming a slice insubstantially the samehorizontal plane as the wire for delivering thestock from said front compartment to the wire, means including atop wallforminga discharge passage leading from said front compartment to saidslice, means establishing said ridge at substantially the samehorizontal level as the wire toprovide for slow speed operation of saidhead boxwith a correspondingly low pressure head of stock above saidridge, a distributor roll journaled within said discharge passage foragitating the stock fiow through said passage to even the fiowdistribution of the stock therethrough, said top wall having asubstantial portion of the length thereof located below the hori zontallevel of said ridge and the remainder thereof located notsubstantiallyhigher than said ridge to maintain said distributor roll submerged instock through the full speed range of operation of said head box, and atleast-oneimperforatebafl'le member extending between said side walls ineach of said compartments, said baffle members being of generallyteardrop configuration in cross section providing a rounded surface onone side thereof tapering to: an apex on the opposite side thereof, and;means mounting said baffle members with the apex of each thereofpointing in the direction of stock flow therepast to cause suddenacceleration of said stock flow followed by more gradual decelerationand thus to effect agitation of said stock with minimum turbulence andtendency to flocculation of the fibers therein.

5; A head box for a Fourdrinier paper machine comprising front and rearwalls and a pair of side walls delining a main chamber for receiving thepaper making stock, partition means dividing said chamber into front andrear compartments, means for delivering stock into the-lower end of saidrear compartment for flow up wardly therein and over said partitionmeans to said front compartment, means forming a slice atv the lower endof said compartment for discharge of the stock therefrom, at least oneirnperforate baffle member extending between. said side walls in each ofsaid compartments, said baflle members being of generally tear-dropconfiguration incross section providing a rounded surface on one sidethereof tapering to an apex. on the opposite side thereof, meansmounting said bafile members extending horizontally across saidcompartments intermediate said partitlOD. means and the adjacent one ofsaid front and rear walls with the apex of each thereof extending in thedirection of the stock flow therepast through the associated saidcompartment, and each said baffle being of a width measured from back tofront of the associated compartment less than the correspondingdimension of said compartment to cause abrupt narrowing of the flowpassage through said compartments for sudden acceleration of the flowof. stock past both sides thereof followed by progressivejwidening ofsuch flow passage for controlled deceleration: of. said. stock. withminimum turbulence.

. 6. A head box for a Fourdrinier paper machine comprising. front andrear walls and a pair of side walls delining; a; mainchamber forreceiving the paper making stock, a.- partition dividing said chamberinto front and rear: compartments and including removable partitionmembersfor varying the effective height of said partition, means: fondelivering stock into-the lower end of said rearcompartment for flowupwardly net-em and oversaid. partition means to said frontcompartment,means forminga slice at the lower-end of said compartment for dischargeof the stock therefrom, at least one imperforatebaffle member extendingbetween said side Walls in each of said compartments, said baftlemembers being'of gen-- erally tear-drop configuration in cross sectionproviding a rounded surface on one side thereof tapering to an apex onthe opposite side thereof, means mounting said baflle members extendinghorizontally across said compartments intermediate said partition meansand the adjacent one of said front and rear walls with the apex of eachthereof extending in the direction of the stock flow therepast throughthe associated said compartment, eachsaid baffle being of a widthmeasured from back to frontof the associated compartment less than thecorresponding dimension of said compartment to-cause abrupt narrowing ofthe'fiowpassage through said compartments for sudden accelerationof theflow of stock past both. sides thereof followed by progressive wideningof such flow passage for controlled deceleration of said stock with.minimum turbulence, and means forming vertically adjustable mountingsfor said bafile members to provide forvarying the positions of saidbafile members in accordance with the height of said partition. I

' 7. A head box for a Fourdrinier paper machine having a forming wireauda breast roll supporting the wire in a wire, means including a topwall forming a discharge passage leading. from said front compartmenttosaid slice; means establishing saidv ridge at substantially the same.horizontal level as the wire to provide for slow speed operation of saidhead box with a correspondingly low pressure head of stock above saidridge, removable partition means above said ridgefor raising the heightof. said front compartment to increase the pressure head of- 3 stocktherein for correspondingly increased speeds of operation, said bottomwall extending. downwardly and forwardly from said ridge toward saidfront wall and cooperating. therewith and with said top wall toestablish.

a constriction. in said discharge passage intermediatesa'id. ridge andsaid slice, said top and bottom walls having: relativelydivergingportions between said constriction and:

said slice to enlarge the portion of said discharge passage definedthereby, a distributor roll journaled' Within. saidenlarged portion ofsaidldischarge passage, and said top: wall having a substantial portionof: the length; thereof-1 located below the horizontal level of saidridge and theremainder thereof located not: substantially higher thansaid ridge to maintain said distributor. roll submerged in; stockthrough the full speed range of operation of said head'box.

'8. A. head box for a Fourdrinier paper machine having a forming wire.and? a breast. roll supporting the wire' in:

a predetermined horizontal plane,- comprising, front and 65 her forreceiving the paper making stock, meansinclud-= rear walls and a pair ofside walls defining a main chanting a bottom wall'forrning a ridgeextending permanently across said main chamber and defining therewith arear and a front compartment, means for delivering stoclciuto: said rearcompartment for flow therefrom over said ridge to said frontcompartment, lips forming a. slice ou.t-'

. let in substantially the. same horizontal plane as thewiro fordelivering'the stock. from said front compartment to the wire,.meansincluding a. top wall. forming at discharge passage leading from. saidfront compartment to -said slice outlet, means establishing said ridgeat substantially the same horizontal level as the wire to provide forslow speed operation of said head box with a correspondingly lowpressure head of stock above said ridge, removable partition means abovesaid ridge for raising the height of said front compartment to increasethe pressure head of stock therein for correspondingly increased speedsof operation, said bottom wall extending downwardly and forwardly fromsaid ridge toward said front wall and cooperating therewith and withsaid top wall to establish a constriction in said discharge passageintermediate said ridge and said slice, said top and bottom walls havingrelatively diverging portions between said constriction and said sliceto enlarge the portion of said discharge passage defined thereby, adistributor roll journaled within said enlarged portion of dischargepassage, said top wall having substantially the entire portion of thelength thereof upstream of said distributor roll located below thehorizontal level of said ridge to maintain said roll submerged in stockthrough the full speed range of operation of said head box, and said topwall being inclined upwardly and forwardly from said distributor roll tosaid slice outlet to promote discharge of entrained air bubbles with thestock flow through said slice outlet.

9. A head box for a Fourdrinier paper machine having a forming wire anda breast roll supporting the wire in a predetermined horizontal plane,comprising front and rear walls and a pair of side walls defining a mainchamber for receiving the paper making stock, means including a bottomwall forming a ridge extending permanently across said main chamberanddefining therewith a rear and a front compartment, means fordelivering stock into said rear compartment for flow therefrom over saidridge to said front compartment, means forming a slice in substantiallythe same horizontal plane as the wire for delivering the stock from saidfront compartment to the wire, means including a top wall forming adischarge passage leading from said front compartment to said slice,means establishing said ridge at substantially the same horizontal levelas the wire to provide for slow speed operation of said head box with acorrespondingly low pressure head of stock above said ridge, said bottomwall extending downwardly and forwardly from said ridge toward saidfront wall and cooperating therewith and with said top wall to establisha constriction in said discharge passage intermediate said ridge andsaid slice, said top wall having a substantial portion of the lengththereof located below the horizontal level of said ridge and theremainder thereof located not substantially higher than said ridge tomaintain said passage filled with stock through the full speed range ofoperation of said head box, means forming a bleed chamber in said headbox located forwardly of said ridge, means defining a slot in said topwall adjacent said constriction and below said bleed chamber andextending substantially the full width of said discharge passage forconducting air bubbles from the stock in said discharge passage to saidbleed chamber, and means for venting said bleed chamber.

10. A head box for a Fourdrinier paper machine having a forming wire anda breast roll supporting the wire in a predetermined horizontal plane,comprising walls defining a main chamber for receiving the paper makingstock, means including a bottom wall forming a ridge extendingpermanently across said main chamber and defining therewith a rear and afront compartment, means for delivering stock into said rear compartmentfor flow therefrom over said ridge to said front compartment, meansforming a slice in substantially the same horizontal plane as the wirefor delivering the stock from said front compartment to the wire, meansincluding a top wall forming a discharge passage leading from said frontcompartment to said slice, means establishing said ridge atsubstantially the same horizontal level as the wire to provide for slowspeed cooperation of said head box with a correspondingly low pressurehead of stock above said ridge, removable partition means above saidridge for raising the height. of said front compart a substantialportion of the length thereof located below the horizontal level of saidridge and the remainder thereof located not substantially higher thansaid ridge to maintain said distributor roll submerged in stock throughthe full speed range of operation of said head box, means forming ableed chamber in said head box located forwardly of said ridge, meansdefining a slot in said top wall located adjacent said constriction andextending substantially the full width of said discharge passage forconducting air bubbles from the stock in said discharge passage to saidbleed chamber, and means for venting said bleed chamber.

11.. A headbox for a Fourdrinier paper machine having a forming Wire anda breast roll supporting the wire in a predetermined horizontal plane,comprising front and rear walls and a pair of side walls defining a mainchamber for receiving the paper making stock, said chamber being open toatmospheric pressure at the top thereof, means forming a partitionextending across said main chamber and defining therein a rear and afront compartment, means defining a stock inlet chamber adjacent thebottom end of said rear compartment, means defining an inlet slotconnecting said inlet chamber with said rear compartment and ofmaterially lesser flow area than said inlet chamber and said rearcompartment, the lower portions of opposed walls of said rearcompartment being arranged to diverge upwardly from the opposed edges ofsaid slot, an imperforate baffle within the bottom end of said rearcompartment mounted between said diverging walls above and incontrolling relation with said inlet slot, said bafile being ofgenerally inverted teardrop shape in cross section providing asubstantially semi-cylindrical lower face and upper side facesconverging to an apex, means maintaining said bafile with said apexpointing upwardly to cause sudden acceleration of the stock flow pastthe lower end thereof followed by gradual deceleration of the stock flowto and past said apex, and means for adjusting said bafile towards andaway from said slot to vary the effective flow area therepast.

References Cited in the file of this patent UNITED STATES PATENTS1,534,080 Russell Apr. 21, 1925 1,727,928 Berry Sept. 10, 1929 1,775,905Lang Sept. 16, 1930 1,886,607 Wood July 12, 1932 1,898,372 Hyde Feb. 1,1933 1,909,150 Bell-Irving et al May 16, 1933 2,062,471 Murray Dec. 1,1936 2,118,491 Chuse May 24, 1938 2,202,890 Berry June 4, 1940 2,205,693Miline June 25, 1940 2,284,098 Lang May 26, 1942 2,308,370 Kellett etal. Jan. 12, 1943 2,325,016 Warren July 20, 1943 2,329,799 Thorsen Sept.21, 1943 2,339,730 Vedder et al. Jan. 18, 1944 2,381,286 Hornbostel etal. Aug. 7, 1945 (Other references on following page) 1 1 UNITED STATESPATENTS 2 Osgood May 9, 1950 V 31 Hornbostel May 30, 1950 7 Lowe Aug. 7,1951 r 5; Heys May 4, 1954 a 8 Goumeniouk May 11, 1954 6.817549 FOREIGNPATENTS Germany May 20, 1910 Germany Oct. 1, 1910 Q d 31, Germany Dec.17, 1912 a 12 Ital-y Oct. 8, 1927 Great Britain July 23, 1931 GermanyNov. 25, 1931 Great Britain Nov. 7,1951 Great Bricain May 21, 1952 GreatBritain Oct. 29, 1952 OTHER REFERENCES Mac'Naughton: Paper Trade 1.,Dec. 26, 1940, pp. 30

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.2,870,690 January 27, 1959 Wesley S. Corbin et al, I

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction and that the saidLetters .Patent should readas corrected below.

Column 5, line 65, for "increasing" read increased column 6, line 4, for"rolls" read roll column 10, line 61, list of referencefi cited, underthe heading "UNITED STATES PATENTS", for the patent number "1,886,607"read 1,866,607

Signed and sealed this 9th day of June 1959.

SEAL) t'test:

KARL AXLINE ROBERT c. WATSON Attesting Oflicer Commissioner of Patents iI I I 1

